Zipstick seems to b the stick of choice amongst most Amiga users I know
However I use one of these mostly:
Its a Quickshot stick and has a great arcade feel to it, buttons are solid and the stick is really procise (digital directions) also works in games that support 2 buttons.
Another cool feature is that it has two leads and a switch 1/2 player and I have it plugged into my A1200 Tower and also my A1200 Desktop at the same time so can easily switch between.
As you probably guessed, I highly reccomend this Joystick.